248 Prof. L. C. Miall on Dicranota ; 
be supposed to contain free oxygen. In each case the 
supply of oxygen can only be renewed with some diffi- 
culty. The Chironomus larva has a closed and rudi- 
mentary tracheal system, but abundance of hemoglobin 
in its blood. The Dicranota larva has if not an open, at 
least an efficient, tracheal system distended with air, 
and no hemoglobin in its blood. 
The reproductive organs of the fly develop early, as in 
all Diptera Nemocera with whose life-history we are 
acquainted.* The testes lie in the 9th segment of the 
larva, and form elongate capsules, giving off, when 
sufficiently advanced, vasa deferentia from the inner 
side of the hinder end. No division of the testes into 
follicles is apparent. I have more than once found it 
filled with ripe spermatozoa mixed with spermatoblasts, 
and this in larve by no means ready for pupation. The 
vasa deferentia are received into glandular vesicule 
seminales, which open by distinct lateral outlets in the 
last segment.t The common ductus ejaculatorius of the 
fly does not exist in the larva. Invaginations of the ex- 
ternal genital appendages of the male fly may be found 
upon the under side of the fore part of the last seg- 
ment. In female larve the ovary may be found full of 
large polygonal multinucleate bodies, which probably re- 
present the follicles of the ova (fig. 31). The oviduct is 
at first asolid cord, apparently ending free behind. The 
early development of the sexual products points to the 
necessity of laying fertilised eggs as soon as possible 
after the imago becomes free. In Lepidoptera (Bombyx 
mort){ and other insects, as well as in Dicranota, the 
spermatozoa have been observed to ripen during the 
larval stage. 
The Pwpa. 
The pupa, as in other Tipulide, is provided with a 
pair of prothoracic respiratory trumpets. These expand 
towards the tip, and are flattened from before back- 
wards. The margin is sharp-edged. Within each 
* Schneider (Zool. Beitriige, i., p. 260) goes so far as to say that 
this is the case with all male Diptera. With respect to the great 
majority of male Diptera, no information is as yet accessible. 
+ This has already been observed in dipterous larve. See 
Palmen’s Paarige Ausfiihrungsgiinge d. Geschlechtsorgane bei 
Insecten, p. 20. 
} H. Meyer, Zeits, f. wiss. Zool., Bd. i., p. 175, 
